Flo is right. The feature of "EXTERNAL_POTENTIAL" is actually what aarondesk needs. In the presence of a STATIC electric field, an optimized structure likely exits. On the other hand, "EFIELD" is primarily for time-dependent wavefunction propagation. Alternatively, since the step of "EFIELD" is always zero during a geometry optimization, one can set "START_STEP 0" to check the existence of the electric field. <div class="gmail_quote">On Thu, Aug 12, 2010 at 7:20 AM, flo <<a href="mailto:fsch...@pci.uzh.ch">fsch...@pci.uzh.ch</a>> wrote: <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> There are two important points. At first Hanning Chen is right, the current implementation uses a time dependent electric field. Performing geometry optimizations, there is no time, therefore this definition of the electric field is meaningless. The second problem Hanning mentions is, that ionic structures don't have a minimum in energy in electric fields (thats why they start to translate). A neutral structure should be possible to optimize, but in the EFIELD part, it was only implemented for dynamics as it was mainly meant to be used in combination with TDDFT methods. If you really want to try to optimize your structure in an electric field, you should try to use the EXTERNAL_POTENTIAL. I haven't used this feature yet, but from my understanding it should do what you want. A proper implementation of a static periodic field, which can be used for MD and geometry optimizations is on my to do list, but I don't know, when I will finish it. regrads Flo <div><div></div><div class="h5"> -- You received this message because you are subscribed to the Google Groups "cp2k" group. To post to this group, send email to <a href="mailto:cp...@googlegroups.com">cp...@googlegroups.com</a>. To unsubscribe from this group, send email to <a href="mailto:cp2k%2Bun...@googlegroups.com">cp2k+uns...@googlegroups.com</a>. For more options, visit this group at <a href="http://groups.google.com/group/cp2k?hl=en" target="_blank">http://groups.google.com/group/cp2k?hl=en</a>. </div></div></blockquote></div>